Generally, a cathode ray tube is a vacuum electron tube in which electron beams emitted from an electron gun are horizontally and vertically deflected to a phosphor screen, thereby emitting light from phosphor layers of the phosphor screen resulting in displaying desired images. The deflection of the electron beams is performed by a deflection unit, which is mounted around the outer circumference of a funnel (the outer circumference of a cone portion substantially forming the vacuum tube) and forms horizontal and vertical magnetic fields.
The cathode ray tube has been mainly used in producing color televisions and computer monitors, and recently has been used in high-end products such as high definition televisions (HDTVs).
However, recently developed flat panel displays, such as plasma display panels, liquid crystal displays, and organic field emission displays, have been spotlighted as the choice of consumers over displays using the cathode ray tube which have excellent display quality but have a large volume vacuum tube (that is, they occupy a large space and are heavy).
In this connection, the cathode ray tube industry has undertaken efforts in reducing the weight of the vacuum tube as much as possible, while maintaining reasonable vacuum-proof strength thereof, as well as shortening the electric field length, thereby slimming the cathode ray tube.
Such efforts appeal to consumers when the image display device using the cathode ray tube as the display unit does not make any significant difference in the space usage compared to flat panel displays.
However, consumers have gradually turned away from image display devices using the cathode ray tube as the display unit because the electric field length of the cathode ray tube cannot be sufficiently reduced due to structural limitations thereof compared to the flat panel displays, even though cathode ray tubes have excellent brightness characteristics and a low production cost.